Intermolecular Triazene Alkene Cycloaddition via Lewis Base Catalysis: Access to Diverse Trifluoromethylated Pyrazolines

Abstract

AbstractA novel approach to chemoselective synthesis of biologically important CF3‐subsituted pyrazolines was developed via a Lewis base catalyzed intermolecular triazene cycloaddition reaction of an array of terminal/internal alkenes with CF3CHN2. This strategy features a catalytic amount of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene, high yields (up to 95 %), wide substrate scope and excellent functional group tolerance (54 examples). Importantly, we preformed scaffold diversification of a panel of known pharmaceuticals, natural products, and bioactive heterocycles to generate the corresponding pyrazoline derivatives with potential broad bioactivities for further development.